Package org.sosy_lab.java_smt.api

Interface OptimizationProverEnvironment

All Superinterfaces:

AutoCloseable, BasicProverEnvironment<Void>

public interface OptimizationProverEnvironment
extends BasicProverEnvironment<Void>, AutoCloseable

Interface for optimization modulo SMT.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	OptimizationProverEnvironment.OptStatus	Status of the optimization problem.

Nested classes/interfaces inherited from interface org.sosy_lab.java_smt.api.BasicProverEnvironment

BasicProverEnvironment.AllSatCallback<R>

Field Summary

Fields inherited from interface org.sosy_lab.java_smt.api.BasicProverEnvironment

NO_MODEL_HELP

Method Summary

Modifier and Type	Method	Description
OptimizationProverEnvironment.OptStatus	check()	Optimize the objective function subject to the previously imposed constraints.
Model	getModel()	Get a satisfying assignment.
Optional<Rational>	lower(int handle, Rational epsilon)
int	maximize(Formula objective)	Add the maximization objective.
int	minimize(Formula objective)	Add minimization objective.
Optional<Rational>	upper(int handle, Rational epsilon)

Methods inherited from interface org.sosy_lab.java_smt.api.BasicProverEnvironment

addConstraint, allSat, close, getModelAssignments, getUnsatCore, isUnsat, isUnsatWithAssumptions, pop, push, push, unsatCoreOverAssumptions

Method Detail

maximize

int maximize(Formula objective)

Add the maximization objective.

Note: push/pop may be used for switching objectives

Returns:

Objective handle, to be used for retrieving the value.

minimize

int minimize(Formula objective)

Add minimization objective.

Note: push/pop may be used for switching objectives

Returns:

Objective handle, to be used for retrieving the value.

check

OptimizationProverEnvironment.OptStatus check()
                                       throws InterruptedException,
                                              SolverException

Optimize the objective function subject to the previously imposed constraints.

Returns:

Status of the optimization problem.

Throws:

InterruptedException

SolverException

upper

Optional<Rational> upper(int handle,
                         Rational epsilon)

Parameters:

epsilon - Value to substitute for the epsilon.

Returns:

Upper approximation of the optimized value, or absent optional if the objective is unbounded.

lower

Optional<Rational> lower(int handle,
                         Rational epsilon)

Parameters:

epsilon - Value to substitute for the epsilon.

Returns:

Lower approximation of the optimized value, or absent optional if the objective is unbounded.

getModel

Model getModel()
        throws SolverException

Get a satisfying assignment. This should be called only immediately after an BasicProverEnvironment.isUnsat() call that returned false. A model might contain additional symbols with their evaluation, if a solver uses its own temporary symbols. There should be at least a value-assignment for each free symbol.

Please note that the prover is allowed to use standard numbers for any real variable in the model after a sat-query returned OptimizationProverEnvironment.OptStatus.OPT. For integer formulas, we expect the optimal assignment.

Example 1: For the constraint 'x<10' with a real x, the upper bound of x is '10-epsilon' (epsilon can even be set to zero). The model can return the assignment x=9. To get an optimal assignment, query the solver with an additional constraint 'x == 10-epsilon'.

Example 2: For the constraint 'x<10' with an integer x, the upper bound of x is '9' (epsilon is irrelevant here and can be zero). The model returns the optimal assignment x=9.

Specified by:

getModel in interface BasicProverEnvironment<Void>

Throws:

SolverException